The water quality of DeKalb County’s Intrenchment Creek is so bad that federal engineers won’t try to fix the habitat there.
That’s what a representative from the U.S. Army Corps of Engineers said on Jan. 19 during a presentation of ways to protect Indian, Sugar, Intrenchment and Snapfinger Creeks.
The so-called ISIS study was authorized by Congress in 1994 to formulate a plan for cost effective and sustainable aquatic ecosystem restoration.
When biologists surveyed Intrenchment Creek in 2005, they found no fish.
Intrenchment Creek has “some beautiful, exquisite habitat,” said Brian Zettle, a biologist with the Corps of Engineers. “It looks like A River Runs Through It. Somebody ought to be out there fishing.
“What should be good habitat and should support a large abundance and diverse group of fish species, we got zero fish,” Zettle said.
The mission of the biologists and engineers working on the ISIS study is not to improve water quality, Zettle said.
“We can go in and fix habitat and fix flow, but we couldn’t address everything that needed to be addressed from a water quality standpoint,” Zettle said. “So we couldn’t get the bang for our buck, so to speak.”
In the ISIS study, the Army Corps of Engineers is conducting stream walks, habitat scoring, fish and macroinvertebrate sampling, and water quality sampling in an effort to stabilize and improve habitat in the target watersheds.
The goal of the scientists is to “look at the habitat and the biological species that make it up and whether there is something we can do through engineering to address the degradation that has occurred there,” Zettle said.
According to the preliminary study, problems that will be addressed include continued loss and degradation of aquatic and riparian habitats, altered hydrology, excessive bank failure and high stream banks, replacement of native tree cover by invasive species are and impaired water quality.
Engineers and biologists hope to “improve the habitat and improve the fish and bug conditions,” said Jamie Childers, a water resource scientist and project manager at Tetra Tech, a company that has contracted with the Army Corps of Engineers to help with the study.
The creeks being studied are “generally urban watersheds that were developed in the 1970s before best management practices and retention ponds were really put in,” Childers said.
The study will address how high peak flows during storms affect the watershed.
“When it rains the water hits the concrete, goes in a ditch …and hits the creeks,” Childers said. “A lot of these backflows cause stream banks to wash out. And that sediment has to settle [and] it usually settles in areas where bugs would attach to rocks or fish would live and hide during those high flows.”
During the public comment session, DeKalb resident Joe Arrington expressed concern about the coordination of the future Army Corps projects with PATH, transportation and public works projects.
“Is there anybody at a higher level looking at how all of these impact each other?” Arrington asked.
Willie Greene, a public works project manager with DeKalb County, said that is job of Ted Rhinehart, the county’s deputy chief operating officer over the infrastructure group.
“We are coordinating, I think, much better today than we were in the past,” Greene said. “We’ve stopped the practice hopefully of paving the street and the next week we come out and tear it up so that we can put in a new water line or a new gas line.”
The Army Corps of Engineers will hold another presentation of the ISIS study on March 6.